Glycoprotein means a protein comprising a moiety of oligosaccharide referred to as a sugar chain.
Recently, glycoprotein has been found to be closely involved with biological processes such as cell adhesion or signaling, and structures of sugar chains which trigger various biological processes have gradually emerged. However, only a small amount of glycoprotein is expressed in a living body for the sugar chain to mediate a biological process, and it is quite difficult to obtain pure glycoprotein in sufficient quantity to determine the chemical and physical properties of the sugar chain.
An asparagine-linked glycoprotein is one of the glycoproteins and ubiquitously found in human serum or ovalbumin. The asparagine-linked glycoprotein is classified into a high mannose-type, a complex type and a mixed type according to characteristics of a branch of the sugar chain and/or constituting sugar. All of these types have a common core sugar chain structure of a penta-saccharide comprising three molecules of mannose and two molecules of N-acetyl glycosamine at the reducing terminal of the chain;

Accordingly, chemical synthesis of the core sugar chain structure shown in the formula above provides the basis for studying the function of asparagine-linked sugar chain.